Antifuses are known elements in semiconductor devices. An antifuse separates a conductor or semiconductor from another conductor or semiconductor, and is characterized by having two states. Initially electrically insulating, when an antifuse is subjected to a high current, it ruptures and becomes conductive, and remains so.
These two distinct states make an antifuse useful in a nonvolatile memory cell. A cell containing, or isolated from a conductor by, an antifuse in an intact, insulating state may be considered to correspond to a zero or a one, while the same cell with a ruptured, conductive antifuse corresponds to the opposite value. This state remains whether power is applied to the device or not.
Antifuses can be made of a variety of materials. A common choice has been intrinsic silicon, as in Kimura et al., U.S. Pat. No. 5,311,039. Silicon dioxide and other oxides have been used as well, as in Rioult, U.S. Pat. No. 3,787,822.
Silicon nitride has been a less frequent choice. Silicon nitride antifuses, however, become particularly advantageous when used in certain structures or paired with certain materials.